Eyewear, Lenses & Vision Products worked example

Lens Grinding Cycle Time at 21% blocking, setup, and handling allowance: a worked example

This scenario runs the lens grinding cycle time calculation on the strong side: 21% blocking, setup, and handling allowance, with every other input held at its documented default. an optical lab manager needs to schedule surfacing and grinding time for a batch of prescription lenses

The inputs for this scenario

  • Prescription lenses to grind: 240 lenses (unchanged)
  • Grinding throughput: 48 lenses / hr (unchanged)
  • Blocking, setup, and handling allowance: 21 % (raised for this scenario; the documented default is 18)

Working through the calculation

  • Applying the documented formula (Base grinding hours = prescription lenses to grind รท grinding throughput) to the inputs above produces each figure below.
  • At this operating point the engine returns 6.05 hr for required lens grinding cycle time, the number this scenario is built around.
  • At this operating point the engine returns 5 hr for base grinding hours.
  • At this operating point the engine returns 21 % for blocking, setup, and handling allowance.
  • At this operating point the engine returns 48 lenses / hr for grinding throughput.

How this compares with the baseline

  • Against the tool's baseline example, where blocking, setup, and handling allowance sits at 18% and the headline result is 5.9 hr, this scenario comes in 2.54% above the baseline at 6.05 hr.
  • Use it when planning a daily surfacing run or quoting turnaround on a batch of Rx jobs. Treat this as a target state: the delta against the baseline quantifies what the improvement is worth before you commit to chasing it.

Results at a glance

  • Required lens grinding cycle time: 6.05 hr (headline result)
  • Base grinding hours: 5 hr
  • Blocking, setup, and handling allowance: 21 %
  • Grinding throughput: 48 lenses / hr

Run it with your numbers

  • Every input above is editable in the live Lens Grinding Cycle Time calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.